Lesson 2 Flashcards
What is the Central Dogma of Biology?
The process by which DNA directs protein synthesis through transcription and translation.
What is the structure of DNA?
Chains of individual nucleotides, two strands with hydrogen bonds between bases, anti-parallel strands.
What are the complementary base pairs in DNA?
- Adenine (A) pairs with Thymine (T) * Cytosine (C) pairs with Guanine (G)
What is semi-conservative DNA replication?
Each offspring gets one copy of the parent DNA during replication.
What is the role of DNA topoisomerases?
Uncoil strands/circles prior to replication.
What is the function of helicase in DNA replication?
Disrupts the bonds between the complementary strands.
What are the three important features of DNA polymerase?
- Elongates DNA strands by adding nucleotides to the 3’ end * Initiates synthesis when RNA primers bind * Has a built-in self-correction mechanism (exonuclease)
What is a replication fork?
The point where two strands are separated and begin replication.
What is the leading strand in DNA replication?
The strand being produced in the 5’ to 3’ direction.
What are Okazaki fragments?
Short DNA fragments produced on the lagging strand during replication.
What provides energy for DNA replication?
Hydrolysis of two phosphate groups from nucleotides.
What is gene expression?
The process by which DNA directs protein synthesis.
What are codons?
Groups of 3 mRNA nucleotides that code for a particular amino acid.
Fill in the blank: The start codon for translation is _______.
AUG
What is the Wobble Hypothesis?
Uracil can bind to the ‘incorrect’ base pair in the last position, allowing one anticodon to act as two.
What is the difference between prokaryotic and eukaryotic gene expression?
- Prokaryotes: No post-processing, mRNA is read immediately * Eukaryotes: Pre-mRNA undergoes splicing by spliceosome
What is vertical gene transfer?
Occurs during reproduction between generations of cells.
What are the three mechanisms of horizontal gene transfer (HGT)?
- Conjugation * Transformation * Transduction
What defines a mutation?
Changes in the genetic material of a cell.
What are point mutations?
Changes where one base pair in a gene is swapped for another.
What are the types of point mutations?
- Silent * Missense * Nonsense
What is a frameshift mutation?
Caused by insertions or deletions that shift the reading frame of mRNA.
True or False: Most mutations in a gene are beneficial.
False
What is the best definition of life according to Gerald Joyce?
Life is a self-sustaining chemical system capable of Darwinian evolution.
What are viruses considered in the context of life?
Obligate intracellular parasites that cannot self-replicate.
What are the general characteristics of viruses?
- Obligate intracellular parasites * No ribosomes, no ATP generation * Very small with few genes
What is a bacteriophage?
A virus that only infects bacteria.
What is the structure of a virus?
- Core: Contains DNA or RNA * Capsid: Protein coat * Envelope: Lipid, protein, and carbohydrate coating
What is the difference between lytic and lysogenic cycles?
- Lytic: Destroys host, produces new phages * Lysogenic: DNA integrates into bacterial chromosome as a prophage
What is HIV classified as?
A retrovirus.
What is reverse transcription?
The process by which retroviruses incorporate their RNA into host DNA.
Fill in the blank: Integrated viral genome in HIV is called a _______.
provirus
